1. Field of the Invention
The present invention relates to a method for manufacturing a polarizer and a laser processing apparatus for manufacturing the polarizer. More particularly, the present invention relates to a method for manufacturing a polarizer having a plurality of stripe lines formed on a surface of the polarizer and a laser processing apparatus for manufacturing the polarizer.
2. Description of the Related Art
A liquid crystal display (“LCD”) apparatus includes an LCD panel and a backlight assembly. The LCD panel includes a thin film transistor (“TFT”) substrate, a color filter substrate, and a liquid crystal disposed between the TFT substrate and the color filter substrate. Since the LCD panel is a passive element that does not emit light by itself, the backlight assembly providing the LCD panel with light has great influence on a brightness of images displayed in the LCD panel.
The LCD apparatus includes polarizing plates disposed on upper and lower surfaces of the LCD panel, such that the liquid crystal operates as a light shutter. The polarizing plate transmits a light polarized in a predetermined direction. The polarizing plate transmits theoretically a maximum of half of the total light generated by the backlight assembly. However, the polarizing plate practically transmits about 43% of the total light generated by the backlight assembly.
In order to increase the amount of light passing through the polarizing plate, a dual brightness enhancement film (“DBEF”) may be disposed between the backlight assembly and the polarizing plate.
However, a cost of the polarizing plate is about 25% to 30% of a total cost of elements of the LCD panel. Additionally, a cost of the DBEF is very high. Therefore, when the LCD apparatus includes the DBEF with the polarizing plate, a manufacturing cost of the LCD apparatus is greatly increased.
In a large or medium sized LCD apparatus, such as a large size television receiver set, a monitor, a notebook personal computer (“NPC”), etc., a size of a mother board has been increased. The number of unit cells is increased, as the size of the mother board is increased. Since a polarizing plate is adhered to each of the unit cells, many processes that adhere the polarizing plate to the unit cell are required for manufacturing an LCD apparatus. Therefore, it is necessary that a polarizer is formed in an area corresponding to the whole mother board. Multi-step, relatively costly and inefficient photolithographic methods of forming a polarizer may include plating the conductive thin film layer together with a photo resist, hardening the photo resist, aligning a mask, exposing, developing, hardening, etching the conductive thin film layer, and stripping the photo resist. In a similar fashion, laser-interference-lithograph methods of forming a polarizer may include plating the conductive thin film layer with a photo resist, soft hardening, hard hardening, patterning the photo resist through exposing the photo resist to excimer laser beams interfering each other without using a photo-mask, etching the conductive thin film layer, and stripping the photo resist. Therefore, a simpler and more cost effective method of forming a polarizer is required.